Fundamental Research On Electrochemical Machining For Leading/Trailing Edges Of Twisted Blades

Blade is the core component of aero-engine.The precision manufacturing of the blades plays an important role in achieving aero-engine performance.Electrochemical Machining(ECM)is a main processing method of aero-engine blade because of its advantages,such as no limitation by mechanical properties of materials,good surface quality,high efficiency,no tool wear.Dissolution mechanism of workpiece materials and cathode design are the basic research topics in the field of ECM.Aiming at the dissolution mechanism of GH4169 alloy,the cathodes design of leading/trailing edges and the full profile along the flow channel,this paper includes the following researches:1.Two types of GH4169 with different heat treatments,solid solution and solution and aging,were studied to analyze their electrochemical behavior.By analyzing the topographical features of the machined surface and the microstructure of the material,it was concluded that the uneven distribution of the metallographic phase and the rich content of the element niobium(Nb)will reduce the surface integrity of the ECMed sample.The surface roughness of the uneven metallographic structure was about Ra 1.378 ?m while it was Ra 0.188 ?m for the smooth structure.A dissolution model was proposed to illustrate the electrochemical behavior of solid solution GH4169.2.To improve the ECM accuracy of the leading/trailing edge,this paper deals with cathode design by optimizing the design plane based on the three-dimensional potential distribution in the interelectrode gap.The optimized planar cathode and a non-optimized planar cathode are designed and a series of corresponding ECM experiments is carried out.The experiments results show that by optimizing the design plane of the cathode leading edge,the allowance difference at the leading edge apex is decreased by 0.062 mm.3.A modified design method for twisted blade full profile along the flow channel was proposed,a multi-physical field coupling simulation model was set up and the research based on model was carried about the full profile along the flow channel.ECM experiments was carried out to verify the machining effect of the full profile modified cathode.4.The full profile modified redesign cathode was applied to an aero-engine twisted blade with a specific machining precision requirement.GH4169 in solution and aging was selected as the workpiece material.Experiments were carried out.According to the measuring results,the accuracy of concave surface was 30.3?m,convex surface was 35?m;the machining accuracy of the leading and trailing edges of the blades was 71 ?m and 59.9 ?m,respectively.